Rep. Tammy Baldwin (D-Wis.) doesn’t like to stray off message — and she’s found one in the “Buffett Rule” that she thinks she can really hold on to.

Baldwin is the House champion of the Buffett Rule legislation, which would impose a tax on individuals making more than $1 million. She is also the Democratic candidate for Senate in Wisconsin, a politically charged state looking to recall its Republican governor and a crucial seat for the Democrats’ hold on the Senate majority.

And while it remains to be seen how well the Buffett Rule message will play in Wisconsin, sources say Baldwin’s attachment to the issue demonstrates her savvy about Washington politics. By latching on to a bill being championed by President Barack Obama’s campaign and Senate Democrats, Baldwin has thrust herself further into the national spotlight. And she’s done it at a time when almost all of the Badger State’s political oxygen is being consumed by Democrats’ efforts to recall GOP Gov. Scott Walker.

“One of the reasons why everyone is so engaged in this is that they’re paying their taxes right now,” Baldwin said in a phone interview between campaign stops at Wisconsin college campuses.

Pressed repeatedly on how the politics of the state is playing into her tax fairness push, Baldwin would not move beyond the Tax Day message, one that also is being pushed especially hard by Senate Democrats. Senate Majority Leader Harry Reid (Nev.) has scheduled a vote today on the Buffett Rule bill because Democrats wanted to move on the legislation as close to the April 17 income tax filing deadline as possible. The bill is not expected to get the 60 votes necessary to advance on the floor, but Democrats hope to use the issue as a bludgeon this fall against Republicans — and presumptive GOP presidential nominee Mitt Romney.

Typically, leadership assigns in-cycle Members to bills it thinks make good political points in order to draw attention to the issue and the lawmaker. Sen. Bob Casey (D-Pa.), for example, was the chief sponsor of the payroll tax cut bill earlier this year, and Sen. Sheldon Whitehouse (D-R.I.) is the Senate sponsor of the Buffett Rule legislation. Both are facing re-election this year.

But House and Senate leadership sources indicated that Baldwin pursued the issue on her own.

“She legitimately picked it up like Senate Democrats did,” one senior Senate Democratic aide said. “Does it have political benefit to her? Of course it does. Having said that, the fact that she has been out front leading on an important issue to the president and the party, I think, is a good thing for her and a good thing for us, both on policy and politics.”

Within a span of four days last week, she was on two national press calls — one with Senate Democratic Conference Vice Chairman Charles Schumer (N.Y.) and another with President Barack Obama’s campaign manager, Jim Messina, and Senate Majority Whip Dick Durbin (Ill.).

Baldwin said she first got involved with the legislation because of an existing working relationship she had with Whitehouse. Last year, she and the Rhode Island Senator teamed up on a resolution regarding the settlement between the Justice Department, state attorneys general and mortgage servicers.

Whitehouse and Baldwin then teamed up on the Buffett Rule after the Wisconsin Congresswoman approached him about the issue.

“Congresswoman Baldwin is a champion for middle-class families in her state, and I’ve been honored to work with her to restore tax fairness,” Whitehouse said in a statement. “She has worked extremely hard on this issue and shown that she’s willing to stand up to the special interests to do what’s right.”

But the road for Baldwin in Wisconsin is not without serious bumps. Republicans almost swept the elections in 2010, picking up the state Legislature, the governor’s mansion and a Senate seat that had been held for nearly two decades by Democrat Russ Feingold. Though Democrats have strongholds in Milwaukee and Madison — the latter is represented by Baldwin in the House — the party has struggled in rural areas of the state.

And as much as Democrats have touted Baldwin’s involvement with the Buffett Rule, Republicans have been quick to attack it. On the day of her press call with Messina and Durbin, the National Republican Senatorial Committee blasted out a statement before the call even took place, challenging the effect of the pending bill and linking Baldwin to Obama.

“As Madison liberal Tammy Baldwin spends the day flacking for President Obama and his far-left tax policies on a campaign conference call, it’s worth noting what she won’t be saying to reporters on the other end of the line,” the email began.

“Tammy Baldwin hasn’t met a tax increase she didn’t like,” NRSC spokesman Lance Trover said in a statement. “The one thing you will not hear Tammy Baldwin say today, as she pushes a tax plan the Wall Street Journal has dubbed a ‘ruse’ is how many jobs it will create and how it will ease American’s pain at the pump.”

Baldwin, of course, sees it differently. She suggested that the tax fairness issue is at the center of the campaign she wants to run in Wisconsin. “People who are just calculating what their marginal tax rates are are coming to me and saying, ‘I can’t believe we’re paying more than Mitt Romney,’ and they’re pretty angry about it,” Baldwin said.